Molded building-block.



W. B. BOLLES.

MOLDED BUILDING BLOCK.

APPLICATION FILED D30. 26, 191;.

1,086,016. Patented Feb. 3; 1914.

65 /3, zfiyzzm 12397 285 51% x I J? f 1 Z COLUMBIA PLANDGRAPH CO.. WASHINGTON. D. c.

UNITED STATES PATENT OFFICE.

WILLIAM B. BOLLES, OF TACOMA, WASHINGTON.

MOLDED BUILDING-BLOCK.

To all whom it may concern Be it known that I, WILLIAM B. vBoLLns, a citizen of the United States, residing at Tacoma, in the county of Pierce and State of \Vashington, have invented a certain new and useful Improvement in Molded Building-Blocks, of which the following is a full, clear, and exact description.

This invention relates to a molded building block of concrete or other suitable plastic material. Its primary object is to so dispose the material that the block, which is preferably rectangular in general outline, will, for the amount of material which it contains, possess the maximum of useful strength to oppose the usual loads and stresses to which it may be subjected in use In some respects the block of this invention resembles the block disclosed in Patent No. 950,609, granted to the same inventor lMaIch 10, 1910; it having the same general shape, proportions and indentured ends as the block of that patent. And as it is adapted to be used in precisely the same manner, in wall or other masonry structures, either with or without metal reinforcing rods extending diagonally through the superposed courses to bind them together, an extended description of such matters herein would be mere repetition and may, for the sake of brevity, be here omitted.

This invention is in the nature of a refinement of the details of the prior block such as adds materially to the value of the invention.

In the drawing, Figure 1 is a plan or top view of a molded concrete building block embodying some of the preferred features of the invention, the development of the indenture or recess in the end of the block being illustrated topographically at the left hand end of the figure by the series of curved and tangential lines indicating the formations at different, serial horizontal planes of elevation. Fig. 2 is a vertical longitudinal section of the block on the line 2, 2 of Fig. 1. Fig. 3 is an end elevation of the same. Fig. i is a perspective view of a block embodying the invention and specially adapted for use at the corners of walls. Fig. 5 is a plan view, on reduced scale, of a single block shown in full lines with the ends of two blocks (shown in dot- V Specification of Letters Patent.

Application filed December 26, 1911.

Patented Feb. 3, 191st.

Serial No. 667,893.

lessdepth than the general thickness of the block. Fig. 8 is alongitudinal section on the line 8, 8 of Fig. 7 and Fig. 9 is an end view of the same. i

The well known characteristics of concrete mixtures are that they possess much greater resistivestrength against compression than against tensile stresses, and a strength about intermediate of the two mentioned against shear and torsion stresses.

In the block of the prior patent referred to the material is so disposed that a preponderance of the mass is located in the lower portion of the block which best adapts it to resist beam strains. And it is further strengthened for beam service by metal reinforcing rods embedded in it at each side below the neutral axis and turned upwardly at their ends. The block of this present invention is, in its preferred form, like its predecessor preferably rectangular in general outline, and is molded with coredout recesses C in its ends which in effect form the block into two major side members or prisms A, A, which are connected by a central tie or pier B.

The inner ends 0 of the recesses are preferably curved or arched and merge into the side walls a which extend outwardly, on diverging lines, from the tangent points to the end of the block which is thus bifurcated at each end, forming a prong a at each side of the recess, which prong tapers off in thickness as it extends outwardly toward the end of the block. This provides an increase of material in each prong from its free end inwardly, which is proportionate to the increment of load moment on the block under stress either as a beam or as a cantaliver. The prongs a on the same sides of the blocks meet at the transverse center of the block and merge into each other, thus forming the side members A, A. They also merge into the central pier B, which ties them together so that each member reinforces the other through their central regions.

The peculiar shape of the indentures or recesses C in the ends of the block is of importance because of its effect upon the disposition of material in the adjacent portions of the prongs a and of central pier B. The arched inner end of each recess is curved on radii, which are of progressively increasing lengths on successive horizontal planes from the top to the bottom of the block, and these radii are struck from center points located on the longitudinal center line of the block at progressively increasing distances apart away from the inner end of the recess, see development at left end of Fig. 1. As a result of these conditions each recess is of decreasing depth, (that is as measured in from the end of the block) progressively downward from the top of the block, it expands in width progressing outwardly from the tangent points on every horizontal plane of the block from the top downwardly, and it also expands in width on every transverse plane in downward progression from the top. In consequence of these dispositions there is an overhang of material into the re cess at both top and bottom of the block, the side walls 0 overhanging when the block stands with its top or right side up while the arched inner end 0 overhangs the recess when the block is positioned bottom side up.

With no intention of fixing arbitrary limits by which the invention might be restricted, but rather to illustrate the present preferred proportions of the block its dimensions are about as follows: Its length is about twice its width and three times its thickness, or say 2 1 x 12 x 8 inches. The superficial areas of the recesses are slightly less than one-third of the gross area of the top or bottom faces of the block, that of the bottom face being slightly but not materially larger than that in the top face. Of the gross cubical contents within its outlines approximately onethird is cored-out recess space and the remaining two thirds is material. The length of the central pier or tie at top is about one-eighth and at bottom about one-third of the over-all length of the block, and in consequence the depth of each recess is at top about seven sixteenths and at bottom about one-third of the length of the block. The width of the inner end of the recess is at top slightly more than one fifth and at bottom slightly less than onehalf the width of the block, while the width of its outer end is, at top about one-halfand at bottom about two-thirds of the width of the block. As before stated, however, these proportions are by no means essentially exact and they may be varied through a wide range within the limits of the invention. As shown in Fig. 1 the intersecting dot-and-dash lines y, y drawn from diagonally opposite corners divide the block into two long triangular side prisms A, A, and two triangular end prisms, the side prisms being solid material, containing most of the entire mass in the block, while the end prisms wholly contain the end indentures or recesses C.

This form of concrete block is easily molded, preferably bottom side up, and the shapes of the end recesses (wider and shorter on one side than on the other and having their inner arched ends sloping toward this side as shown) are not only advantageous in the disposition of the material but they facilitate the withdrawal of the core prints without danger of breaking off sharp corners or edges of the green concrete material. With the recesses narrower at the top than at the bottom the prongs at each side are wider and contain more material in their upper than in their lower portions on any cross sections, and they are thereby strengthened to meet cantaliver stresses. It has been demonstrated by experiment that the fracture line across a prong of this block is es cillating and cannot be predicated with any greater accuracy than that it lies in a zone of weakness distant in from the extremity of the prong about one-quarter of the whole length of the block, say on or near the rough fracture lines X shown in Figs. 1, 2 and 5. This zone of weakness lies approximately in or near to the intersection region of the inner recess wall, where the change in structural character from the curving arch to the straight tangent wall occurs and it may in some measure be due to this change.

The prongs, as before stated, are thicker in their upper than in their lower parts and this disposition of material strengthens them through this zone of weakness against cantaliver stresses, but it is not advantageous in a block subjected to a beam load in which the thicker parts above the neutral axis would be under compression while the thinner parts below it would be subject ed to tensile strains, an exact reversal of the most advantageous conditions for concrete mixtures under beam stresses. In order to strengthen these lower portions of the block, particularly across their zones of weakness, and better adapt them to carry beam loads, metallic reinforcing rods D may be embedded in the lower portion of each side member A of the block below the neutral axis. These rods are of particular value at the zones of weakness across and well beyond which they should extend in order to effectively reinforce these areas, and for this particular purpose they may be made and disposed like D in Fig. 2, wholly embedded within one prong. Outside of this special purpose, however, they are not objectionable and may be advantageously extended farther, say to the end of the block, as shown at D in Fig. 2, or like D in Fig. 1, or D of the same figure. These rods may be of any desired shape in cross section, two forms, square and round being shown in the drawing. As before set out the area of material surface is slightly more than two-thirds of the gross area of the block. The greater portion of this material surface lies in proximity to the center of the block where the surfaces of the pier or tie B are added to those of the side members A, A. In a wall composed of these blocks and laid up as shown in Figs. 5 and 6 with staggered joints in alternate courses, owing to the peculiar form of the blocks with their indentured ends the proportion of surface in bearing is about one-half of the gross surface area of the block or about three-fourths of the net material surface. As shown by the shaded or cross-hatched surface portions 9 in Fig. 5, these areas in bearing lie entirely within the side memhere A, A, and wholly off the central pier B.

Tests have demonstrated that the region of greatest strength in the block lies in the pier B and in the adjacent parts when the pier is made the full depth of the block from top to bottom and that this strength is greatly in excess of the requirements in a well balanced block. This will therefore admit of a material reduction of the size of the pier and it is proposed, while still maintaining a high factor of safety, to effect a saving of material through reducing the depth of the pier and to accomplish this by depressing its surface either on both sides as shown at e in Figs. 7, 8 and 9, or wholly on one side as may be found most convenient in molding the blocks.

Having thus described the invention, what is claimed as new and useful is:

l. A molded building block having in each end a cored-out recess which recess is of progressively decreasing depth and increasing width from. the top to the bottom of the block whereby the ends of the block are bifurcated forming prongs which progressively increase in cross sectional thickness from their bottoms to their tops, the pairs of prongs lying on the same side of the longitudinal center line of the block merging and uniting to form side members of the block which side members are united by a centrally placed connecting tie, the cubic space occupied by said recesses occupying about one third of the gross cubical contents within the outlines of the block.

2. A molded building block having in its end cored out recesses, which recesses are of progressively decreasing depth and increasing width from the top to the bottom of the block, said recesses thereby forming prongs, which prongs are of progressively decreasing length and decreasing thickness from the top to the bottom of the block, the pairs of prongs on each side of the longitudinal center line of the block merging and uniting to form side members of the block, with a centrally located tie unitof the block and of increasing width as they extend outwardly from their inner ends to the ends of the block, thereby forming prongs at each side of the recesses, which prongs are of progressively length and thickness extending downwardly decreasing fromthe top of the block and of decreasing width extending outwardly toward the end of the block.

4. A molded building block having coredout recesses in its ends, which recesses are formed with arched inner end walls merging into tangential side walls which diverge as they extend outwardly away from their tangent points, the arched inner ends being curved progressively downward from the top of the block on radii of increasing lengths and struck from centers located at increasing distances apart away from the inner end of the recesses, thereby forming the block into two integral side members, and a central pier connecting the side members, the pier increasing progressively in length from its top downwardly and the side members extending away from said pier in prong formation at the sides of the recesses, the prongs increasing progressively in thickness from their free ends inwardly and increasing progressively in thickness and length from their bottoms upwardly.

5. A molded building block having coredout recesses in its ends which recesses increase in width from the top downwardly, and from their inner ends outwardly, whereby the pron formations of the ends of the block at eac side of the recesses are of in creasing thickness extending from their bottoms to their tops and extending from their free ends inwardly with reinforcing metal rods embedded in each side of the block below a plane parallel with and substantially midway between the top and bottom surfaces of the block.

6. A molded buildin block having coredout recesses in its encl s which recesses are formed with arched inner ends which are curved on radii of increasing length from the top to the bottom of the block, the recesses decreasing in depth from'the top to the bottom of the block and increasing in width both from their inner ends outwardly and from the top to the bottom of the block, whereby the prong formations of the ends of the block are of increasing thickness from their bottoms upwardly, and from their free ends inwardly, and also of increasing lengths from their bottoms to their tops, and are provided with reinforcing elm 1,086,016

metal rods embedded in each side of the block, the prongs being of progressively deblock below a plane parallel With and sub creasing length and decreasing thickness stantially midway between the top and botfrom the top toward the bottom of the block. tom surfaces of the block. In testimony whereof, I hereunto affix my 5 7. A molded building block having as the signature in the presence of two Witnesses. 15

end portions cored out recesses the sai re- I m cesses being of progressiveli decreasing VILLIAM ROLLED depth and increasing Width from the top to Nitnesses: the bottom of: the block, the recesses forming H. P. BURDIOK,

10' prongs Which project from the body of the G. Down MGQUESTEN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). C. 

